The present invention relates to a process of manufacture of a composite material whereby a mixture of fibrous material, alkali silicate and fluosilicate is fashioned, said mixture being molded and hardened.
From DE-OS No. 2 300 724 a similar manufacturing process is known in which one seeks a very short hardening time by adding to the mixture a practically stoichiometrical quantity of fluosilicate. However, experiments have shown that such a short hardening time is not absolutely desired because it is associated with important disadvantages. During the manufacture of a mixture of fibrous material it may already happen that too little time is at disposal for permitting a good mixing up and a subsequent molding of the mixture before the hardening process starts or has progressed too far. In order to avoid the forming of a crystalline, sandlike structure of the hardened binding agent the fluosilicate is added finely grinded. With regard to the fact that fluosilicates are toxic, the addition of high amounts of grinded fluosilicates is unfavourable. The mechanical strength, in spite of the high amount of fluosilicate, is not very high because no linear growing chains are produced but instead, as already explained, a sandlike structure of the SiO.sub.2. The fire-proof quality also leaves much to be desired.
An object of the present invention is to attain high mechanical strength and fire-proof quality associated with more favourable technical conditions of manufacturing.